Are there replacement drivers? What is the going price for a pair of CX 100s?

Replacement drivers are still available from a B&O dealer. The alternative is to re-foam the existing ones if that is the only (common) problem.  Going price will depend on condition - from £40 to £200 say $80 to $400 - but that is based on UK prices - USA may differ.... 

Please note these replacement drivers have been produced quite some time ago. Foam rot continues on shelves as well - even when boxed, although the pocess slows down a little... So if you buy replacement drivers you might end up buying drivers that will last for a few years only. It's best to replace the foam rings with new - freshly pressed - foam rings or rubber rings for maximum durability.

It is interesting though that my CX50s and CX100s have no sign of foam rot at all. The CX50s were bought by my wife for me about 17 years ago and the CX100s maybe 3 years later. Do we think different environmental conditions  (CX50s always in a bathroom and Cx100s always in a sitting room) or have I been lucky?

I recently collected a set of CX100's on Ebay with all of the four inch drivers in pretty rough condition.  The cost of re-foaming was lower than I expected and only Aus$35 each.  After re-assembly, one driver was still "scratching" badly so I opted for a proper B&O spare.  I was even more surprised when the new driver only cost me $48 so I should have probably got four new ones to start with.  Anyhow, the speakers are now working well and giving excellent sound for the small units that they are.

Geoff